In the telecommunications industry, the use of switching jacks to perform cross-connect and monitoring functions is well known. The jacks may be mounted to replaceable cards or modules, which in turn may be mounted in a chassis, and multiple chassis may be mounted together in an equipment rack. Modules for use in co-axial environments are described in U.S. Pat. No. 5,913,701, which is incorporated herein by reference. Modules for use in twisted pair applications are described in U.S. Pat. No. 6,116,961, which is also incorporated herein by reference. Cross-connect modules are also used with fiber optic communications systems.
FIG. 1 shows a prior art cross-connect arrangement of the type used for co-axial applications. The depicted arrangement includes two jack modules 20, 22. The jack modules 20, 22 may be mounted in separate chassis that are in turn mounted on separate racks. Each jack module 20, 22 is cabled to a separate network element (i.e., piece of telecommunications equipment). For example, jack module 20 is connected to equipment 24 by cables 26, and jack module 22 is connected to equipment 28 by cables 30. The pieces of equipment 24 and 28 are interconnected by cross-connect jumpers 32 placed between the two jack modules 20 and 22. Each jack module 20, 22 includes IN and OUT ports 34 and 36 for direct access to the equipment's input and output signals. Each module 20, 22 also includes X-IN and X-OUT ports 35, 37 for providing direct access to the cross-connect input and cross-connect output signals. Ports 34-37 provide a means to temporarily break the connection between the pieces of equipment 24 and 28 that are cross-connected together, and to allow access to the signals for test and patching operations. The jack modules 20, 22 also include monitor ports 38 for non-intrusive access to the input and output signals of each piece of telecommunications equipment 24, 28.
A typical telecommunications central office includes many jack modules and a large number of bundled cables interconnecting the modules. Consequently, absent indicators, it is difficult to quickly determine which two jack modules are cross-connected together. To assist in this function, the jack modules 20, 22 include indicator lights 40 wired to power 42 and ground 44. Switches 46 are positioned between the indicator lights 40 and ground 44. The indicator lights 40 are also electrically connected to pin jacks 48 located at the rear of the jack modules 20, 22. The pin jacks 48 provide connection locations for allowing the tracer lamp circuits corresponding to each of the modules 20, 22 to be interconnected by a cable 50 (i.e., a wire). The cable 50 is typically bundled with the cross-connect cables 32. When either switch 46 is closed, the indicator lamps 40 corresponding to both of the jack modules 20, 22 are connected to ground and thereby illuminated. Thus, by closing one of the switches 46, the two jack modules 20, 22 that are cross-connected can be easily identified by merely locating the illuminated tracer lamps. Examples of tracer lamp units are described in U.S. Pat. Nos. 4,840,568, 5,145,416, and 5,393,249, the entire disclosures of which are incorporated herein by reference.